1. Field of the Invention
The present invention relates to an internal combustion engine with a torque converter mounted on a four-wheel buggy (saddle type vehicle for rough terrain running) or the like.
2. Description of Related Art
A related art device is described in Japanese Utility Model Laid-open No. Hei 1-180054. In this related art device, a crank chamber, a torque converter chamber, and a transmission chamber are separated from each other. Hydraulic oil is supplied to the torque converter by an oil pump driven from a transmission shaft.
In the related art, the crank chamber, the torque converter chamber, and the transmission chamber are separated by walls. Accordingly, if an oil passage dedicated to the torque converter for supplying the hydraulic oil to the torque converter is provided, a sealing structure is complicated. If lubricating oil for an internal combustion engine is also used as the hydraulic oil for the torque converter, the return oil from the torque converter is returned directly to the atmosphere in the crankcase rather than to an oil reservoir. This causes the production of oil mist in the crankcase, reducing breather function. However, if an oil passage extending through the wall between the crank chamber and the torque converter chamber is formed as a return oil passage from the torque converter independently of the lubrication for the internal combustion engine, the whole structure is undesirably complicated.